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Finite or discrete collections of geometric objects. Packings, tilings, polyhedra, polytopes, intersection, arrangements, rigidity.

2 votes
0 answers
83 views

Finding the nearest Apollonian gasket

Given a set $\mathcal{P}$ of $n$ points in the euclidean plane, how can a set $\mathcal{V}$ of $n$ vectors be determined, that has minimal length-sum and renders $\lbrace p_i+v_i\rbrace$ to be the cen …
Manfred Weis's user avatar
  • 13.2k
0 votes
1 answer
56 views

Extremality of Triangles with Corners from Planar Convex Hulls

I am looking for proofs of or counterexamples to the following assumptions: if the corners of a triangle are chosen from a compact subset $\mathcal{S}$ of the Euclidean plane then all three corners …
Manfred Weis's user avatar
  • 13.2k
1 vote
Accepted

Constructing a polygon of $n$ facets from a set of positive values representing the length o...

No, it is not always possible, because it is not always possible to partition the (cyclic) sequence of edge-length into 3 portions of adjacent edges, for whose sums the triangle inequality holds; e.g. …
Manfred Weis's user avatar
  • 13.2k
4 votes
2 answers
270 views

Probabilities of four points being in convex/deltoid configurations

Question: what is the probability that four distinct points in general position in the Euclidean plane are in convex configuration, depending on the number of leaf nodes in their Minimum Spa …
Manfred Weis's user avatar
  • 13.2k
2 votes
2 answers
132 views

Algorithm for Finding all Empty Ellipses Locked by a Set of Points

Is there an algorithm for reporting all empty ellipses, that are locked by a finite set $\mathcal{P}$ of points in the euclidean plane? An ellipse is considered empty, if no inner point is an elem …
Manfred Weis's user avatar
  • 13.2k
2 votes
1 answer
44 views

Name for a Property of Certain Polylines

Question: Is there already a name for polylines in the euclidean plane, that have the property, that no interior of none the triangles, defined by one of the polyline's endpoints and a non-a …
Manfred Weis's user avatar
  • 13.2k
1 vote
1 answer
92 views

Convexity of the Voronoi cells of higher-dimensional polyhedra

let a convex polytope $\mathcal{P}$ in $E^n$ be defined as in the tag-description with the additional requirement that their volume be strictly positive. let further the Voronoi Cells $VC(f)$ of $\mat …
Manfred Weis's user avatar
  • 13.2k
0 votes
1 answer
49 views

Constructing a polygon from another with collinearity constraints

Let $P$ be a closed polygon defined by the sequence $p_0,\,\dots,\,p_{n-1},p_0$ of points. Question: how can one construct, with straightedge and compass alone, another sequence of points $q_0,\,\dot …
Manfred Weis's user avatar
  • 13.2k
2 votes
0 answers
100 views

Sequence of numbers related to line-segment intersections

Question: what is known about the sequence $\mathbb{X}\subset \mathbb{N}_0$ such that for each $k\in \mathbb{X}$ there exists a set of $n$ points in general position in the Euclidean plane such that t …
Manfred Weis's user avatar
  • 13.2k
1 vote
1 answer
501 views

Has this curious "duality" of weighted $K_4$ already been noticed?

A complete symmetric graph with $n=4$ vertices, i.e. a $K_4$ is the disjoint union of three perfect matchings $M_{\text{min}},M_{\text{mid}},M_{\text{max}}$ of which $M_{\text{min}}$ denotes the light …
Manfred Weis's user avatar
  • 13.2k
1 vote

Has this curious "duality" of weighted $K_4$ already been noticed?

This should rather be a comment, posting it as an answer is to give a visual clue that there is something in the vein of a proof. Elaborating on Timothy Chow's insightful comment it suffices to consid …
Manfred Weis's user avatar
  • 13.2k
1 vote
0 answers
86 views

Detecting points inside the convex hull with inner products

Given a finite set $P$ of $n\gt d+1$ points in $d$-dimensional euclidean space. Under the assumption that the points of $P$ are in general position in the sense that $\lbrace p_{i_1},\dots,p_{i_d}\rbr …
Manfred Weis's user avatar
  • 13.2k
4 votes
0 answers
104 views

"Shape Aware" Trees

Have these kinds of geometric spanning trees already been described? all three are Minimum Spanning Trees of points that are elements of open disks, the only difference being in how the edge-weight …
Manfred Weis's user avatar
  • 13.2k
2 votes
0 answers
274 views

What is a hull in the most general mathematical sense?

I have implemented an algorithm that filters the edges of simple complete graph with weighted edges according to a criterion that is inspired by elementary planar geometry and, to my surprise, in the …
Manfred Weis's user avatar
  • 13.2k
2 votes
1 answer
69 views

Density of Intersection-Points of "Rational" Lines in the Euclidean Plane

consider the set of lines defined by all pairs of points $\lbrace[(u,v),(u-v,v+u)],\ u,v\in\mathbb{N}\rbrace$ in the euclidean plane Question: what is kown about the density of the set of intersectio …
Manfred Weis's user avatar
  • 13.2k

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